The alpha-adrenergic antagonists phenoxybenzamine, phentolamine, clozapine, yohimbine, and prazosin cause a non-selective increase in norepinephrine turnover in all the brain regions studied. The beta-adrenergic antagonists propranolol, timolol, metaprolol, pindolol and butoxamine did not affect norepinephrine turnover in a uniform fashion. For instance, timolol, metoprolol and butoxamine decreased MOPEG-SO4 levels in the midbrain-hippocampus while propranolol and pindolol were without effect in this region. Propranolol increased, while butoxamine decreased, norepinephrine turnover in the cerebral cortex. Both propranolol and pindolol increased turnover in the corpus striatum. Thus, if beta-adrenergic blockers lower blood pressure by a central mechanism, this action is not reflected in uniform changes in noradrenergic nerve activity in the brain.